I must have original WoW ?Did you activate your account by e-mail? Aren't your password longer than 16 symbols? Did you try both set realmlist login.kronos-wow.com and set realmlist wow.twinstar.cz in your realmlist.wtf file? Are you able to log in with your credentials on www.twinstar.cz ?
Still didn't work.Yes, you can and you should open wtf file in notepad and save it without changing the name or extension (watch out and don't produce realmlist.wtf.txt).
Of course, you must have 1.12.1 client. It's mentioned on http://www.kronos-wow.com/how-to-connect/ which you presumably followed.